Apparatus and method for cooling a combustor

ABSTRACT

A combustor includes a combustion chamber and an interior wall circumferentially surrounding at least a portion of the combustion chamber and defining an exterior surface. A plurality of turbulators are on the exterior surface. The combustor further includes means for preferentially directing fluid flow across a predetermined position of the turbulators. A method for cooling a combustion chamber includes locating a plurality of turbulators to an exterior surface of the combustion chamber and preferentially directing fluid flow across a predetermined position of the plurality of turbulators.

FIELD OF THE INVENTION

The present invention generally involves an apparatus and method forcooling a combustor. Specific embodiments of the present invention mayinclude a combination of a flow sleeve and turbulators arranged atpredetermined locations on an exterior surface of the combustor toimprove the heat transfer from the combustor.

BACKGROUND OF THE INVENTION

Gas turbines are widely used in industrial and power generationoperations. A typical gas turbine includes an axial compressor at thefront, one or more combustors around the middle, and a turbine at therear. Ambient air enters the compressor, and rotating blades andstationary vanes in the compressor progressively impart kinetic energyto the working fluid (air) to produce a compressed working fluid at ahighly energized state. The compressed working fluid exits thecompressor and flows through nozzles in the combustors where it mixeswith fuel and ignites to generate combustion gases having a hightemperature, pressure, and velocity. The combustion gases flow to theturbine where they expand to produce work. For example, expansion of thecombustion gases in the turbine may rotate a shaft connected to agenerator to produce electricity.

It is widely known that the thermodynamic efficiency of a gas turbineincreases as the operating temperature, namely the combustion gastemperature, increases. Combustion gas temperatures exceeding 3000° F.are therefore desirable and fairly common in the industry. However,conventional combustion chambers and transition pieces that channel thecombustion gases out of the combustor are typically made from materialsgenerally capable of withstanding a maximum temperature on the order ofapproximately 1500° F. for about 10,000 hours. Therefore, it is desiredto provide some form of cooling to the combustion chamber and/ortransition piece to protect them from thermal damage.

A variety of techniques are known in the art for providing cooling tothe combustion chamber. For example, U.S. Pat. Nos. 5,724,816,7,010,921, and 7,373,778 assigned to the same assignee as the presentinvention each describe various structures and methods for cooling acombustor and/or transition piece of a combustor. However, continuedimprovements in the structures and methods for cooling combustorcomponents would be useful.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention are set forth below in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

One embodiment of the present invention is a combustor having acombustion chamber and an interior wall that circumferentially surroundsat least a portion of the combustion chamber. The interior wall definesan exterior surface and a longitudinal centerline. A plurality ofturbulators are on the exterior surface of the interior wall. A sleevecircumferentially surrounds at least a portion of the interior wall, andthe sleeve defines a plenum between the interior wall and the sleeve. Aterminal end of the sleeve forms a perimeter around the interior wall,and the perimeter has a bellmouth shape around at least a portion of theperimeter.

Another embodiment of the present invention is a combustor having acombustion chamber and an interior wall circumferentially surrounding atleast a portion of the combustion chamber. The interior wall defines anexterior surface and a longitudinal centerline. A plurality ofturbulators are on the exterior surface of the interior wall. Thecombustor further includes means for preferentially directing fluid flowacross a predetermined position of the plurality of turbulators.

The present invention may also include a method for cooling a combustionchamber. The method includes locating a plurality of turbulators to anexterior surface of the combustion chamber and preferentially directingfluid flow across a predetermined position of the plurality ofturbulators.

Those of ordinary skill in the art will better appreciate the featuresand aspects of such embodiments, and others, upon review of thespecification.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof to one skilled in the art, is set forth moreparticularly in the remainder of the specification, including referenceto the accompanying figures, in which:

FIG. 1 is a simplified cross-section of a combustor according to oneembodiment of the present invention;

FIG. 2 is a perspective view of a transition piece according to oneembodiment of the present invention;

FIG. 3 is a perspective cutaway of a transition piece according to asecond embodiment of the present invention; and

FIG. 4 is a perspective cutaway of a transition piece according to athird embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to present embodiments of theinvention, one or more examples of which are illustrated in theaccompanying drawings. The detailed description uses numerical andletter designations to refer to features in the drawings. Like orsimilar designations in the drawings and description have been used torefer to like or similar parts of the invention.

Each example is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that modifications and variations can be made in thepresent invention without departing from the scope or spirit thereof.For instance, features illustrated or described as part of oneembodiment may be used on another embodiment to yield a still furtherembodiment. Thus, it is intended that the present invention covers suchmodifications and variations as come within the scope of the appendedclaims and their equivalents.

FIG. 1 shows a simplified cross-section of a combustor 10 according toone embodiment of the present invention. As shown, the combustor 10generally includes one or more nozzles 12 radially arranged in an endcap 14. For clarity, the nozzles 12 are illustrated in the figures ascylinders without any detail with respect to the type, configuration, orinternal components of the nozzles 12. One of ordinary skill in the artwill readily appreciate that the present invention is not limited to anyparticular nozzle type, shape, or design unless specifically recited inthe claims.

A liner 16 and transition piece 18 circumferentially surround acombustion chamber 20 downstream of the end cap 14. The liner 16 andtransition piece 18 define an exterior surface 22 and a longitudinalcenterline 24 for the flow of compressed working fluid or air throughthe combustion chamber 20. The liner 16 and transition piece 18 maycomprise a single, continuous piece that circumferentially surrounds thecombustion chamber 20. Alternately, as shown for example in FIG. 1, theliner 16 and transition piece 18 may each comprise a separate interiorwall joined by a seal 26 so that each circumferentially surrounds atleast a portion of the combustion chamber 20. As shown in each of thefigures, either or both of the interior walls 16, 18 may have agradually decreasing circumference that focuses or concentrates thecombustion gases exiting the combustor 10.

The combustor 10 further includes a plurality of turbulators 28 on theexterior surface 22 of either or both interior walls 16, 18. Theturbulators 28 may comprise angled protrusions or indentions on theexterior surface 22 of one or both of the interior walls 16, 18 todisrupt the laminar flow of the compressed working fluid as it passesover the exterior surface 22 of the interior walls 16, 18. Theturbulators 28 thus increase the effective surface area of the exteriorsurface 22 of the interior walls 16, 18 and may induce swirling in thecompressed working fluid. The disruption of the laminar flow on theexterior surface 22 and increase in the effective surface area of theexterior surface 22 both contribute to increasing the swirl component ofthe velocity of the compressed working fluid over the exterior surface22 to improve the coefficient of the transfer across the interior walls16, 18 and facilitate cooling of the interior walls 16, 18. In addition,the increased turbulence in the compressed working fluid caused by theturbulators 28 may enhance the subsequent mixing of the compressedworking fluid with the fuel to enhance the combustion in the combustionchamber 20.

The turbulators 28 may be protrusions or indentions on the exteriorsurface 22 having virtually any geometric shape, including circular,rectangular, triangular, trapezoidal, or any combination thereof. Theturbulators 28 may be cast, welded, bolted, or otherwise attached to theexterior surface 22 of the interior walls 16, 18 using any suitablemethod known in the art and capable of withstanding the high temperatureenvironment of the combustor 10. In particular embodiments, for exampleas shown in FIG. 2, the turbulators 28 may comprise a stepped protrusion30 extending from the interior walls 16, 18. The stepped protrusion 30may have a generally rectangular base 32 with a pointed end 33, similarto a fin with a winglet, distal from the interior walls 16, 18. Thestepped protrusion 30 may enhance heat transfer by producing eddies orvortices over the exterior surface 22 of the interior walls 16, 18. Asshown in FIG. 2, the turbulators 28 or stepped protrusions 30 may bearranged in an array of rows and columns to redirect the compressedworking fluid flowing across the exterior surface 22 of the interiorwalls 16, 18 to further enhance the cooling provided by the compressedworking fluid. In addition, a higher concentration of the turbulators 28or stepped protrusions 30 may be located at a predetermined position 34on the exterior surface 22 of the interior walls 16, 18. Thepredetermined position 34 may be an area on the exterior surface 22 ofthe interior walls 16, 18 that typically has a higher operatingtemperature based on empirical measurements and/or mathematical models.In this manner, the beneficial cooling effects provided by theturbulators 28 or stepped protrusions 30 may be enhanced at thepredetermined position 34 known or expected to have higher operatingtemperatures.

The combustor 10 further includes means for preferentially directingfluid flow, for example the flow of the compressed working fluid, acrossthe predetermined position 34 of the plurality of turbulators 28.Referring again to FIG. 1, the means for preferentially directing fluidflow may comprise a sleeve 36 with a terminal end 38 alignedapproximately 90° from the longitudinal centerline 24 of the internalwalls 16, 18. The sleeve 36 circumferentially surrounds at least aportion of one or both of the interior walls 16, 18 and is generallyconcentric with one or both of the interior walls 16, 18. As a result,the sleeve 36 defines a plenum 40 between the interior walls 16, 18 andthe sleeve 36. The terminal end 38 of the sleeve 36 forms a perimeteraround the interior walls 16, 18 and further includes a bellmouth shape42 around at least a portion of the perimeter. As shown in FIG. 1, forexample, the perimeter of the terminal end 38 of the sleeve 36 has acontinuous bellmouth shape 42 around the entire perimeter. In thismanner, the sleeve 36, terminal end 38, plenum 40, and bellmouth shape42 combine to preferentially direct fluid flow through the plenum 40 andacross the plurality of turbulators 28. As shown in FIG. 1, inparticular embodiments the sleeve 36 may further include a plurality ofapertures 44 to further allow fluid flow across the turbulators 28,although the presence of apertures 44 in the sleeve 36 is not a requiredstructure for the means for directing fluid flow or a limitation of thepresent invention unless specifically recited in the claims.

FIG. 3 shows a perspective cutaway of the transition piece 18 portion ofthe combustion chamber 10 according to an alternate embodiment of thepresent invention. In this embodiment, the means for preferentiallydirecting fluid flow comprises the sleeve 36, terminal end 38, plenum40, and bellmouth shape 42 as previously described with respect toFIG. 1. In this particular embodiment, however, the terminal end 38 isaligned approximately 45° from the longitudinal centerline 24 of theinternal wall 18. As shown in FIG. 3, the bottom portion of the terminalend 38 has a bellmouth shape 42, while the top portion of the terminalend 38 is generally straight. In addition, the means for preferentiallydirecting fluid flow in this particular embodiment includes at least oneenlarged opening 46 in the sleeve 36. The size and location of theenlarged opening 46 in the sleeve 36 may be selected to control theamount and location of fluid flow, and thus cooling, that ispreferentially directed onto or across specific turbulators 28 on theexternal surface 22 of the interior wall 18. For example, the enlargedopening 46 may be sized so that the means for preferentially directingfluid flow covers less than approximately 90%, 80%, 70%, or 60% of theinternal wall 18 and/or turbulators 28. In addition, or alternately, theenlarged opening 46 may be located proximate to the predeterminedposition 34 previously described with respect to FIG. 2 having a higherconcentration of turbulators 28 and/or known or expected to have higheroperating temperatures.

FIG. 4 shows a perspective cutaway of the transition piece 18 portion ofthe combustion chamber 10 according to yet another alternate embodimentof the present invention. In this embodiment, the means forpreferentially directing fluid flow comprises the sleeve 36, terminalend 38, plenum 40, and bellmouth shape 42 as previously described withrespect to FIG. 1. In this particular embodiment, however, the terminalend 38 is aligned approximately 135° from the longitudinal centerline 24of the internal wall 18. As shown in FIG. 4, the top portion of theterminal end 38 has a bellmouth shape 42, while the bottom portion ofthe terminal end 38 is generally straight. As with the embodiment shownin FIG. 3, the means for preferentially directing fluid flow in thisembodiment again includes at least one enlarged opening 46 in the sleeve36. The size and location of the enlarged opening 46 in the sleeve 36may be selected to control the amount and location of fluid flow, andthus cooling, that is preferentially directed onto or across specificturbulators 28 on the external surface 22 of the interior wall 18. Forexample, the enlarged opening 46 may be sized so that the means forpreferentially directing fluid flow covers less than betweenapproximately 90%, 80%, 70%, or 60% of the internal wall 18 and/orturbulators 28. In addition, or alternately, the enlarged opening 46 maybe located proximate to the predetermined position 34 previouslydescribed with respect to FIG. 2 having a higher concentration ofturbulators 28 and/or known or expected to have higher operatingtemperatures.

One of ordinary skill in the art will appreciate that each of theembodiments described and illustrated in FIGS. 1 through 4 may be usedto provide a method for cooling the combustion chamber 20. The methodmay include locating a plurality of turbulators 28 to the exteriorsurface 22 of the combustion chamber 20 and preferentially directingfluid flow across a predetermined portion of the plurality ofturbulators 28. The predetermined portion of the plurality ofturbulators 28 may exist, for example, near the bellmouth shape 42 ofthe distal end 38, under the enlarged opening 46, or any other desirablelocation on the exterior surface 22 of either or both of the interiorwalls 16, 18. The method may further include concentrating the pluralityof turbulators 28 at the predetermined position 34 on the exteriorsurface 22 of the combustion chamber 20, as shown, for example, in FIG.2.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other and examples areintended to be within the scope of the claims if they include structuralelements that do not differ from the literal language of the claims, orif they include equivalent structural elements with insubstantialdifferences from the literal languages of the claims.

1. A combustor comprising: a. a combustion chamber; b. an interior wallcircumferentially surrounding at least a portion of the combustionchamber, wherein the interior wall defines an exterior surface and alongitudinal centerline; c. a plurality of turbulators on the exteriorsurface of the interior wall; d. a sleeve circumferentially surroundingat least a portion of the interior wall and having a plurality ofopening therethrough, wherein the sleeve defines a plenum between theinterior wall and the sleeve and a plurality of apertures in the sleeve;and e. a terminal end of the sleeve, wherein the terminal end of thesleeve forms a perimeter around the interior wall and the perimeter hasa flared opening around at least a portion of the perimeter to define anairflow inlet opening.
 2. The combustor as in claim 1, wherein theinterior wall has a gradually decreasing circumference.
 3. The combustoras in claim 1, further comprising a higher concentration of theplurality of turbulators at a predetermined position on the exteriorsurface of the interior wall.
 4. The combustor as in claim 1, whereinthe plurality of turbulators comprise a stepped protrusion extendingfrom the interior wall having a pointed end distal from the interiorwall.
 5. The combustor as in claim 1, wherein the perimeter of theterminal end of the sleeve has a continuous bellmouth shape around theperimeter.
 6. The combustor as in claim 1, wherein the terminal end ofthe sleeve is aligned approximately 45° from the longitudinal centerlineof the interior wall.
 7. The combustor as in claim 1, wherein theterminal end of the sleeve is aligned approximately 90° from thelongitudinal centerline of the interior wall.
 8. The combustor as inclaim 1, wherein the terminal end of the sleeve is aligned approximately135° from the longitudinal centerline of the interior wall.
 9. Acombustor comprising: a. a combustion chamber; b. an interior wallcircumferentially surrounding at least a portion of the combustionchamber, wherein the interior wall defines an exterior surface and alongitudinal centerline; c. a plurality of turbulators on the exteriorsurface of the interior wall; and d. means for preferentially directingfluid flow across a predetermined position of the plurality ofturbulators, wherein the means defines an airflow inlet opening and themeans includes a plurality of apertures therethrough.
 10. The combustoras in claim 9, wherein the interior wall has a gradually decreasingcircumference.
 11. The combustor as in claim 9, further comprising ahigher concentration of the plurality of turbulators at a predeterminedposition on the exterior surface of the interior wall.
 12. The combustoras in claim 9, wherein the plurality of turbulators comprise a steppedprotrusion extending from the interior wall having a pointed end distalfrom the interior wall.
 13. The combustor as in claim 9, wherein themeans for preferentially directing fluid flow covers less thanapproximately 90% of the plurality of turbulators.
 14. The combustor asin claim 9, wherein the means for preferentially directing fluid flowincludes a terminal end having a bellmouth shape around at least aportion of the terminal end.
 15. The combustor as in claim 14, whereinthe terminal end is aligned approximately 45° from the longitudinalcenterline of the internal wall.
 16. The combustor as in claim 14,wherein the terminal end is aligned approximately 90° from thelongitudinal centerline of the internal wall.
 17. The combustor as inclaim 14, wherein the terminal end is aligned approximately 135° fromthe longitudinal centerline of the internal wall.